TFTs are a particular class of field effect transistors made of thin films. These thin films form a semiconductor layer (such as an active layer of the TFT constituting the channel), dielectric layers (such as a gate insulating layer, an etch stop layer, or a passivation layer) and metallic contacts (such as a gate, a drain, or a source of the TFT). These thin films are formed over a supporting substrate, for example, glass. At least some known TFTs are implemented in liquid crystal active matrix displays (LCDs), which are widely employed for computers and television monitors. Furthermore, at least some known TFTs are implemented in organic light emitting diodes (OLEDs) which are also used for active matrix displays.
Generally, TFTs include a gate insulating layer for insulating the gate terminal. In particular, at least some known TFTs are provided with a gate insulating layer formed from silicon oxide (e.g., SiO2). The gate insulating layer is a key factor in the performance of TFTs. In particular, the gate insulating layer greatly influences the breakdown voltage and the leakage current of the TFT.
Accordingly, it is desirable to provide a deposition method and a deposition system for forming a gate insulating layer, which facilitates improving the performance of a TFT.